This invention relates to a clamping device and more particularly to a clamp for securing a pump jack pole to a wall or roof brace, and the like.
In connection with scaffolding equipment, there is generally utilized a number of upright poles on which ride pump jacks which in turn support horizontal scaffolding. Such equipment is generally utilized in the construction field and especially in connection with the installation of exterior siding on housing structures and especially aluminum siding.
Typically, for the upright poles there has been utilized a pair of wooden 2 by 4's, usually of Douglas fir. The pair of 2 by 4's are coupled together to form a single unitary upright pole. In the aforementioned parent application, there is described a novel aluminum upright pole which has a rubberized coating on one side thereof and serves a similar purpose for utilization as a pump jack pole.
When assembling the scaffolding unit, the upright poles must be secured to the wall or roof of the housing structure on which the scaffolding is placed. For such purposes, there is typically utilized a V-shaped brace with hinged foot locks on the feet of the brace for attachment to the building structure. At the head of the brace, one of the V-shaped members typically supports side links. The two side links in conjunction with the brace member form a U-shaped yoke which fits around the substantially square upright pole. Typically, at the distal ends of the side links of the yoke there are slots. A bolt is inserted through the slot transversely across the distal ends of the yoke and is held in place by means of wing nuts.
The prior art clamping arrangement has been found in need of improvement. Firstly, since the bolt fits transversely across the ends of the yoke and is retained by means of wing nuts, there has been found very little leverage for suitably tightening the bolt in place and as a result, frequently the clamping arrangement loosens causing movement of the upright pole and possible accidental collapse of the scaffolding.
In addition, since the wing nut is tightening the bolt in a lateral direction, it has been found that cross threading of the wing nut on the bolt frequently occurred which accordingly damaged the bolt and either prevented its further use, or if it was used it prevented adequate tightening and clamping of the pump jack pole.
With the prior art arrangement, the bolt itself formed a separate piece from the yoke and additionally required other parts to retain the bolt in place. Either wings nuts were utilized at both ends of the bolt, or a wing nut was used at one end and with a hole formed through the bolthead, a nail was placed transversely through the hole to hold the bolt in place. In either case, there were numerous pieces that had to be retained and frequently all of these pieces were not found and resulted in loss of time, failure to adequately clamp the poles, and extra cost to replace parts.
Additionally, and perhaps one of the major problems, since the tightening of the bolt was done in a transverse position with respect to the upright pole, there existed a moment of force during the tightening of the bolt which caused possible rotation of the upright pole during clamping. Also, since the clamping was achieved by pulling the two links together, the pole was only held in place on its two sides, but was not fully held in place on its opposing two sides since the bolt was necessarily spaced from the surface of the pole.